Although various methods and structures have been provided for recovery of waste heat, in so far as is known to me, conventional counter-current spray towers heretofore have not provided for more than one transfer unit for either mass or energy transfer systems. In part, this is because in such conventional spray tower designs, droplets fall through a rising gas in which the gas superficial velocity is at only a fraction of the terminal velocity of entering droplets.
In contact devices, it is important to observe that as the average droplet diameter decreases, the total surface area for the liquid increases (area is proportional to 1 divided by the diameter of the average droplet). Also, an average contact period (dwell time) for a droplet entering a contact chamber depends on the terminal velocity of the droplet, its trajectory, and the path distance, as well as upon the velocity of the gas encountered.
Unfortunately, conventional spray tower design has not matched nozzle design developments. For the most part, conventional spray tower designs have ignored the use of any droplet diameter component, as a consequence of using design methods such as the Souder-Brown equation, in which no droplet diameter component appears. Thus, it would be desirable to provide an improved spray tower that utilizes improved spray nozzle technology to develop a narrow range of liquid droplet particle size. Also, it would be desirable to enhance spray tower performance by providing spray nozzles that maximize droplet surface area. Finally, it would be desirable to provide a spray tower in which dwell time is optimized, so as to optimize heat transfer between the droplet and the gas stream through which it flows.